1. Field of the Invention
The present invention relates to a method and an apparatus for detecting an abnormality in a battery pack system. The battery pack system is composed of a plurality of battery pack blocks, each of which is constituted by connecting a plurality of cells in series, that are connected with one another by a combination of serial connection and parallel connection.
2. Description of Related Art
A conventional battery pack system typically incorporates a battery pack block constructed by connecting a plurality of cells in series. For example, six cells are connected together in series so as to provide a battery module, and 20 to 30 units of such battery modules are juxtaposed and connected together in series, whereupon the battery pack block is realized. In the battery pack system, the temperature, voltage, and current of the battery pack block are detected based on output signals from various sensors (not shown) mounted on the battery pack block. Based on the detection results, various control operations and abnormality detection are executed.
Moreover, in keeping with the demand for a higher-capacity, higher-power battery pack system, a battery pack system 100 as shown in FIG. 4 has been proposed that is composed of a plurality of the above-described battery pack blocks 11 connected with one another by a combination of serial connection and parallel connection. In such a battery pack system, a single current sensor 12 is typically disposed in a region where total current flows.
However, the battery pack system shown in FIG. 4 poses the following problem. When an abnormality occurs, e.g., when a rise in battery resistance occurs in the cell incorporated into any of the battery pack blocks 11, the result appears only partly in the current sensor 12. This makes accurate abnormality detection difficult. Even if the abnormality can be detected, it is impossible to immediately determine which one of the battery pack blocks 11 suffers from the abnormality. Thus, appropriate measures cannot be readily taken.